A body of work such as Pasteur's is inconceivable in our time: no man would be given a chance to create a whole science. Nowadays a path is scarcely opened up when the crowd begins to pour in.

The quote by Jean Rostand reflects on the changing nature of scientific progress and the opportunities available to individuals in modern times compared to the past. Rostand is commenting on the extraordinary impact of Louis Pasteur, whose work in microbiology and medicine revolutionized science. He suggests that in Pasteur's time, an individual could still make profound contributions and create a whole science by themselves. However, in contemporary times, scientific progress is more collaborative, and no single person has the same opportunity to work independently on such a grand scale.

Rostand’s reference to the crowd pouring in implies that modern scientific fields have become so specialized and competitive that as soon as a new path or discovery is made, many others quickly follow. The collective nature of scientific advancement today contrasts with the more individualistic, pioneering efforts of past figures like Pasteur. This shift may reflect the increasing complexity of modern science, where interdisciplinary collaboration and larger research teams are essential for tackling the world's most pressing scientific challenges.

The origin of this quote lies in Rostand’s own reflections on the state of science and society. As a French biologist and philosopher, Rostand was keenly aware of the changes in the scientific community during the early 20th century. He witnessed the rise of specialization in research and the growing bureaucratization of science, which he saw as diminishing the scope for individual researchers to make monumental, independent discoveries like those of Pasteur.

In essence, Rostand’s quote highlights the evolution of scientific work from the age of individual pioneers to the present era of collaborative and highly specialized research. He suggests that while scientific progress is undoubtedly still occurring, it is now a more collective effort, where individual contributions are often less visible on the grand scale of discovery. The quote serves as both an appreciation for past breakthroughs and a commentary on the changes in how science is practiced today.